Lisa Jasa, CropWatch Editor, Univerity of Nebraska-Lincoln
Only a fraction of the nation's corn crops are in the ground, which is a significant change from last year. Planting continues but snow, rain, and storms remain an on going challenge for farmers. For example, only about 3% of the Nebraska's corn crop had been planted by Sunday, according to the Nebraska office of the National Agricultural Statistics Service. This is significantly down from 40% last year and the five-year average of 26%. This week crop specialists at UNL and neighboring universites in the Corn Belt offer recommendations and a review of historical data that show planting date often is not the key factor to yield response.
This week UNL agronomist Bob Klein writes: "While producers need to be aware of the final planting dates for crop insurance (Figures 1-3), it's important that they not plant under field conditions that could result in less than desirable stands and/or uneven emergence." Klein, the cropping systems specialist for western Nebraska, continues: "The 1% penalty per day for up to 20 days for planting after the planting deadline could be a lot less than the result of planting in field conditions that do not contribute to good stands and even emergence. The 1% per day is taken off your APH. If you have an APH of 190 bu/ac and you were 10 days late, your level of coverage (70%) or guarantee would be calculated on 171 bu/ac (190-19) instead of 190 bu/ac."
"Planting in wet soils also can contribute to soil compaction and resulting emergence problems," Klein said. "Always keep your crop insurance and Farm Service Agency personnel informed."
Paul Jasa, UNL extension engineer, agrees. "Delay planting until soil and temperature conditions are right. While we may be late according to the calendar, we're not late according to other indicators. Planting into wet soils can cause compaction, leading to uneven stands and yield loss in compacted areas."
One fix? Lighten the load, Jasa recommends. "Tractors are the heaviest axle you can have on the field. If you're carrying a 1,000-gallon tank and your fertilizer typically weighs 10-11 lb per gallon, you're adding five tons to the existing tractor weight. If you have large fertilizer tanks, fill them half full and refill more often."
To avoid sidewall compaction when planting into wet soils, don't plant too shallow if you have angled closing wheels. (See the April 16, 2010 CropWatch articles listed below for further planting tips to avoid compaction in wet soils.)
Another tip for good soil structure: "If you have to do tillage, keep it shallow. Better yet, don't till," said Jasa. "And if you're taking along a chain in case you get stuck, you probably shouldn't be in the field yet."
Comparing Planting Date to Final Yield Data
If you're feeling ill at ease because this week's weather is keeping you out of the field, know that other states in the Corn Belt are facing similar planting delays. The following articles from our extension neighbors explore historical data that indicate planting delays may not hurt yield as much as might be expected.
Corn Concepts: Planting Progress, Germination and Emergence by Nathan Mueller in the South Dakota State University Department of Agonomy. Mueller charts final corn yields for the last eight years in South Dakota against planting progress as of May 1. The highest average yield was recorded in 2009 when only about 10% of the state's corn had been planted by May 1. He notes that planting date certainly isn't the key determinate in yield. The lowest average yield was recorded in 2012 when approximately 57% of the corn crop had been planted by May 1 before drought conditions took a toll. Mueller's article was posted May 2 on iGrow, a website of the South Dakota State University Extension.
Weather Forecast Delays Corn Planting, but Late Planting Does Note Foretell Lower Yields by Warren Pierson and Roger Elmore, both in the Iowa State University Department of Agronomy. Much like Nebraska, as of April 28 only 2% of Iowa's corn acres had been planted. They chart yield trends to an April 30 planting date over the last 30 years. "Having more acres planted by April 30 does not necessarily relate to high yields, and perhaps even slightly lower yield," they write in the ISU Integrated Crop Management News. Also see Elmore's April 29 blog posting, I am not going to plant! I am not going to plant! ... Should I plant?
In an April 23 article, The Planting Date Conundrum for Corn, Bob Nielsen of the Purdue University Department of Agronomy asks "Why is it that every corn agronomist known to man preaches about the importance of timely planting and yet the statewide statistical data suggest that planting date accounts for only 23% of the variability in statewide yields from year to year?" Nielsen goes on to examine data and yield trends, noting that statewide averages for planting date and yield are not strongly related in Indiana. He also suggests that farmers be patient and not "mud in" corn, which can have far worse effects on emergence than delayed planting. Nielsen's article was on the Corny News Network.
In an April 24 posting to the University of Illinois Bulletin, Planting Delays and Corn Prospects, agronomist Emerson Nafziger writes "Despite our anxiousness to finish planting by the end of April, Illinois data over the past 20 years do not show that early planting alone boosts yields." Is timely planting important? Yes, says Nafziger, but if it doesn't occur, it's not "game over." He also cautions growers not to plant into wet, compacted soils which could compromise later plant development.
Recap of UNL CropWatch Planting Articles